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SECTION 2: TRAPEZOIDAL AND CIRCULAR CHANNEL ANALYSIS PROGRAMS <br /> basins. The culvert has a bottom slope of 0.01 feet per foot, and the Manning's <br /> roughness coefficient for the pipe is assumed to be 0.015. The Normal Depth of <br /> flow in the culvert is to be determined for a flow rate of 400 cfs. <br /> 2.4.4.2.2 Solution of Example for Circular Channel <br /> Using Chart 51 of the FHWA's "Design Charts for Open-Channel Flow" (FHWA 1961) , <br /> the Normal Depth of flow in the circular channel under the stated conditions is <br /> approximately 4 feet. The flow velocity is approximately 16 feet per second. As <br /> indicated by the example screen display, the Circular Channel Analysis program <br /> provides the same results. <br /> 2.4.4.2.3 Example Screen Display for Circular Channel <br /> CIRCULAR CHANNEL ANALYSIS <br /> Normal Depth COMPUTATION <br /> Flow Rate (cubic feet per second) 400 <br /> Channel Bottom Slope (feet per foot) .0100 <br /> Manning's Roughness Coefficient (n-value) .015 <br /> Channel Diameter (feet) 8 <br /> *** RESULTS *** <br /> Normal Depth (FEET) 4.03 <br /> Flow Velocity (feet per second) 15.77 <br /> Froude Number 1.561 <br /> Velocity Head (feet) 3.86 <br /> Energy Head (feet) 7.89 <br /> Cross-Sectional Area of Flow (square feet) 25.37 <br /> Top Width of Flow (feet) 8.00 <br /> P ess Enter key to repeat. R to Print Re ort or Esc to return to Main Menu <br /> 2.5 CRITICAL DEPTH FOR TRAPEZOIDAL .OR CIRCULAR CHANNELS <br /> 2.5.1 Purpose of Critical Depth Procedure <br /> Critical Depth occurs when the flow in a channel has minimum specific energy. <br /> Specific Energy refers to the sum of the depth of flow and the velocity head. <br /> At Critical Depth, the velocity head is equal to one-half the average depth of <br /> flow. Critical Depth depends only on the channel shape and flow rate. <br /> It is sometimes useful to compute Critical Depth in order to analyze the type <br /> of flow profile which will occur in a particular channel. <br /> 2.5.2 Required Input Data for Critical Depth Procedure <br /> In order to compute the Critical Depth of flow in a channel, the program <br /> DODSON & ASSOCIATES, INC. THE DODSON HYDRAULICS LIBRARY, PAGE 20 <br />